Reichardt's Dye Incorporation into Lotion

[Atreya]

Hey guys! This is Atreya. I'm a high school student in the middle of a science project. I wish to create a lotion that is compounded with Reichardt's dye, a solvatochromic dye, as a way to detect bacteria present on hands. I was wondering if anyone was familiar with any processes of binding water insoluble dyes with lotions? Or if there were any ideas of how to do so? Thanks so much for your time and input.

[SciB]

You could probably dissolve the Reichardt's dye in dimethyl sulfoxide and add it to the lotion base. Surfactants like polysorbate are also often used in pharmaceutical preparations to emulsify hydrophobic chemicals.

I am not clear, however, on how Reichardt's dye will indicate bacteria. As I understand the solvatochromic properties of the chemical it changes color as the solvent is changed from polar to nonpolar. I don't see how the bacteria at the numbers found on a person's hands would change the polarity of your lotion. Can you explain your rationale for this project?

Sybee

[Atreya]

Thanks so much for your response and time. I have found a patent of wipes created that have been compounded with Reichardt's dye (as well as other solvatochromic dyes) and have been indicative of the presence of S. aureus as well as other bacteria and there have been given concentrations as to how much is needed to produce a color change in the Reichardt's dye. I was thinking of doing experimentation in two major "procedures". I wish to first see how much of S. epidermis needs to be present (I am unable to use S. aureus) in order to produce the color change and the color the dye changes to (quantified by photoshop). Then I wish to combine the dye with lotion to see if it would work as well. Thanks so much for your input and time again.

Atreya

[SciB]

You're welcome Atreya. Please keep us posted on how the project is going.

Do you have a url for where you read about this patent for using Reichardt's dye? I am curious about how the presence of bacteria is supposed to cause the dye to change color. I don't see how it can work unless there are really a lot of bacteria present and that would not be the case normally on a person's hands.

I'm assuming that the goal is to have a lotion that one applies to the hands that will reveal bacterial contamination. Is it supposed to work with ANY bacteria or just Staph?

Good luck!

Sybee

[Atreya]

Thank you again for the quick reply. The URL is https://www.google.com/patents/US7399608. I might have to test how much bacteria is needed for a visible change in Reichardt's dye.

Yes, the goal is for the lotion to function in bacterial detection. And the dye does work with many different bacteria but signals different color changes which I aim to document.

Thanks for your time!

Atreya

[SciB]

Hi Atreya,

I read part of the patent background information and the dye would indeed be a great addition to a lotion or soap if it really works as well as they say it does to reveal bacteria. As a scientist, however, you must always be skeptical of claims like this until you have tried it yourself and proven that it works.

How are you planning to test the dye? We can help you with experimental design and statistical analysis if you describe your methods in detail.

Sybee

[Atreya]

Hello,

Thank you so much! I was planning on doing two to three different stages of experimentation. At first, I would like to see the color change Reichardt's dye has on Staphylococcus epidermis (since I am unable to use lethal bacteria) compared to Micrococcus epidermidis (which was determined as one of the most common bacteria present on human skin). I will grow these bacteria on identical petri dishes and have identical concentrations. Then, for the second phase, I would like to test the minimal bacterial present of Staphylococcus epidermis needed to illicit a color change. Then, for the third stage of experimentation, I would like to see if incorporation into lotion would work as effectively as a color change when in contact with the bacteria. Does this experimentation process sound viable? I would like to have at least thirty repeated trials for each stage. Thanks again for your time and input.

From,
Atreya Mishra

[SciB]

Hi Atreya,

Yes, your plan is a good one and it is the way a scientist would go about it--step by step, verifying each stage of the process before moving on to the next.

One thing to be especially careful of in your experiments is the chemical environment when you test the solvatochrome. The color reaction results from a change in polarity so you will have to think about the polarity differences between agar or liquid culture medium and lotion. Lotions usually have oils that are hydrophobic and emulsifiers to keep them in solution and this will create a chemical environment that has a different polarity from that of agar.

What I am trying to say is that just because you see a color change at a certain titer of bacteria in culture medium, that does not mean that the Reichardt's will have the same sensitivity in lotion.

Do you have any idea how many S epidermidis are likely to be found on normal human skin? If this number is way below the sensitivity of your assay then it won't work. You need to know approximately how many bacteria would be on the skin in order to set up the sensitivity test.

Good luck!

Sybee

[Atreya]

Thank you. That's true. I will look into the amount of bacteria present on human skin. Thanks so much fro your help. Do you have any suggestions for improvement of my experimentation? Thanks again for your time.

Atreya

[SciB]

You are welcome, Atreya.

What you need is some preliminary data. Right now all we are doing is speculating. You don't even know if Reichardt's will show any color change with S epi. Do you have the dye and the bacteria? If so you should try an experiment right away with different amounts of bacteria to see: (1) do you see any color change and (2) what is the minimum level of S epi that gives a color change?

Repost when you have some data, or if you have further questions.

Good luck!

Sybee